IMO- Mathematics Olympiad Class 9: Questions 632 - 635 of 919

Mean of 11 observations is 17.50, if one observation value 15 is deleted. The mean of remaining observations is ________

Two cars start from opposite places on a main road, 150 km apart. First car runs for 25 km and takes a right turn and then runs 15 km. it then turns left and runs for another 25 km and then takes the direction to reach the main road. In the meantime, due to minor break down the other car has run only 35 km along the main road. What would be the distance between the two cars at this point?

If the mean of 10 observations is 20 and that of another 15 observations is 16, then the mean of 25 observations is ________

There are four pillars W, X, Y and Z of different heights. Three spiders A, B, C and D start to climb on these pillars simultaneously. In one chance A climbs on W 10 cm but slips down 2 cm. B climbs on X 15 cm but slips down 7 cm. C climbs on Y 14 cm but slips down 6 cm. D climbs on Z 17 cm but slips down 11 cm. if each requires 70 chances to reach the top of the pillar, what is the height of the shortest pillar?